Resilient mounting



Jan. 18, 1949. RQY KUBAUGH 2,459,741

' RESILIENT MOUNTING Original Filed Oct. 27. 1942 2 h h l LEROY M.KUBAUGH 2 Sheets-Sheet 2 Jan. -18, 1949. 1.5 'Ro'Y M. KuBAusH RESILIENTMOUNTING Original Filed Oct. 27, 1942 M w m w M W Q 5 w m n s .m m w m aw a n M w M x Pat'entecl Jan. 18, 1949 RE SILIEN T MOUNTING Le Roy M.Kubaugh, Akron, Ohio, assignor to The Firestone Tire & Rubber Company,Akron, Ohio. a corporation of Ohio Original application October 27,1942, Serial, No.

463,505, now Patent No. 2,367,830, dated January 23, 1945. Divided andthis application August 21, 1944, SerialNo. 550,449 i 3 Claims.

This invention relates to resilient mountings and more especially itrelates to improved resilientmountings comprising rubber such as areused for vibration insulators or for other yielding or flexibleconnections interposed between supporting and supported structures.

The chief objects of the invention are to provide in an improved mannerfor reducing the sag or permanent set of the rubber element or elementsof resilient mountings of the character mentioned; to increase thecapability of static deflection of the mounting and thereby to reduceits natural frequency of vibration. More specifically the invention aimsto provide a simple means for obtaining pre-compression of the rubberstructure of resilient mountings of the character mentioned and therebyto achieve the attendant benefits of such pre-compression; and

to provide means whereby the amount of precompression of the rubber maybe changed.

For illustrative purposes, the invention will be shown and describedwith relation to the resilient. mounting shown in Fig. 4 of U. S. PatentNo. 2,047,493 to Curt Saurer, issued July 14, 1936, upon which mountingthe present invention is an improvement.

Of the accompanying drawings:

Fig. 1 is a transverse section through one em-, bodiment oi theinvention, in operative association with a supporting structure and asupported structure;

Fig. 2 is a plan view of the improved mounting as seen from line 2-2 ofFig. 1;

' Fig. 3 is a transverse section through the resil- This application 'isa division of my copending' application, Serial No. 463,505 filedOctober 1942, now Patent No. 2,367,830.

Resilient mountings of the character mentioned commonly are used forsupporting vibratory struc- *tu'resupon' non-vibratory structuresssuchas the mounting of an electricalmotor orfsan internal combustion engine'upon'a floor or ceiling. Also they are used for mounting a vehiclemotor upon the' frame of the vehicle. In either case an im- "portantfunction of the mounting is to absorb 'and/orsuppr'essthe motorvibrations and preventor retardfitheir transmission to the supportingstructure's Although prior rubber mountings.

such -as the Saurer mounting aforementioned,

a have given excellent all-around performance, they were believed to becapable'of improvement in their vibration-dampening characteristic, thatis, their transmissibility could be decreased.

The improving of the prior resilient mountings according to the presentinvention is based on the theory that:

The natural frequency of a rubber mounting is given closely by theformula. I

I 3.13 cycles per second wherein fn=natural or resonant frequency, andd=deflection in inches under static load. a

Transmissibility is given by:

wherein E=transmissibiiity and fd=the distlmbof the invention to. aspecific rubber vibration in-.

sulator, the aforementioned Saurer mounting'is employed, and saidmounting, in normal condition, is deformedand narrowed by laterall .di-

rected pressure so that the rubber elements thereof have a determinate.amount of precompression. The term pm-compression" as used hereinrefers to compressive stress of the rubber elements, maintained by theother elements of the mountig. irrespective of the stresses placedthereon by the structure supportedthereby.

Referring to the drawings, there is shown. in Fig. 3 thereof atransverse section of the Saurer resilient mounting aforementioned, thesame being in normal unstressed condition. Said mounting is designatedasv a whole bi t e character S, and consists of parallel, spaced-apart.

spective lateral faces of thechanneland to the adjacent lateral facesof. theurespective angle strips l0. At least the bottom face of each'cushion i2 is arcuate as shown, the arrangement being such that as thechannel ii is depressed or de- 3 hosted during use the bottom face ofeach eushion progressively makes contact with the surface I! of thesupporting structure (not shown) upon which the lateral strips aremounted. with the result that the cushions offer progressivelyincreasing resistance to such deflection. The structure may be of anylength desired, but preferably is made in relatively long lengths sothat shorter lengths may be cut therefrom. Both lateral strips II andthe channel strip ii are formed with bolt holes, as shown, to receivethe bolts that secure them toa supporting structure and supportedstructure respectively. Preferably each angle strip II is so shaped thatthe included angle deflned by the legs thereof is greater than 90degrees. and said strips are so arranged that the upstanding legsthereof converge toward each other. The lateral legs of the channel. Iidiverge from their common base, the arrangement being such that thechannel legs and the adjacent legs of the lateral strips iii are insubstantial parallelism transversely as well as longitudinally.

Referring now to Figs. 1 and 21 of the drawings, the resilient unit S isshown in combination with means by which pre-compression is imparted tothe rubber elements thereof. As shown therein. said means consists of aninverted channel-like structure II having outwardly turned marginalflanges II, it. The depth of the channel structure II is somewhatgreater than the height of the mounting S. and the greatest width of thechannel of the structure is less than the greatest width of the mounting8 between the upstanding legs of the lateral strips lil thereof.Furthermore. the sides of the structure I diverge from the base thereofat substantially the same angle as the included angle between therespective legs of the said lateral strips ii) of the mounting 8. Likethe latter, the structure ll may be made initially in a relatively longlength, shorter lengths if required-being cut therefrom, as indicated bythe transverse broken lines, Fig. 2. The channel structure I! isreinforced at spaced points throughout its length by re-entrant ribs orwebs i1, i1 formed diagonally across the rounded corners at the junctureof its base portion with the respective sides of the structure. Theflanges it of the structure I! are formed with bolt holes ll and thebase of the structure is formed with a longitudinal series of centrallypositioned apertures II, is. The ribs H, the bolt holes II, and

- the apertures it are in alignment transversely of ,.deformation anddeflection of the rubber bodies ii of the resilient unit as to put saidbodies under compressive stress, referred to herein as "precompression.are fully telescoped, the flanges ll of the channel are in juxtapositionwith the laterally extending legs of the strips I0 of the unit 8, andthe bolt holes ll of the channel are in registry with the bolt holes ofsaid strips it. Thus both elements may be secured to an underlyingsupporting. structure II by bolts or cap screws that extend through saidaligned bolt holes. In the assembled mounting the bolt holes in thechannel ii of the resilient unit are in alignment with the apertures llof the channel structure II. Thus a supported structure. shown at 2i,may be secured to the channel of the resilient unit by means of a boltor bolts 22 that extend through the said apertures ll, each boltextending through a spacer sleeve 23 disposed between the channel Ii andthe supported structure 2 I.

In the assembling of the mounting, the structure II is forced down upona unit 8, or alternatively, the latter is forced into the channel of thestructure i5. This operation readily is accomplished since the sides ofthe resilient unit '5 and the channel structure I! are complementallyBecause of the pre-compression imparted to the rubber bodies of themounting, the tendency of the said bodies to sag or to take a permanentset is materially reduced. Furthermore, the rubber bodies have greaterstatic deflection than they would have if not compressed, with theresult that the natural frequency of vibration of the mounting isreduced. This fact is verifled by the following test data made with amounting 2 inches in length. the rubber bodies being of 40 durometerhardness as molded.

Not compressed Under pro-compression Load Deflection calculated LoudDeflection calculated l2lbs .050" 14.0 cycles/sec.... 11.5 lbs. .050"14.0 cycles/sec. 22 lbs... .100" 9.9 cycles/sec... 21.5 lbs.. .100" 9.0cycles/sec. 33 lbs... .150" 8.! cycles/sec..... 3l.3ibs.. .150 8.1cycles/sec. 42 lbs... .200 7.0 cycles/sec"... 39.0 lbs .200" 7.0cycles/see. 54 lbs... .350! 6.26 cycles/seem. 47.5 lbs.. .250" cmcycles/see.

The foregoing data clearly shows that the natural frequency of vibrationis inversely proportional to the deflection under static load, and thatthe same deflection in a pre-compressed mounting may be obtained with alighter static load than in an uncompressedmounting,

The invention provides in a simple manner for imparting pre-compressionto a resilient mounting unit of the character described, whereby theattendant benefits of pre-compression are achieved.

In the embodiment of the invention shown in Fig. 4, the rubber bodies ofthe resilient unit 8 are placed under rare-compression by means of achannel-like structure of adjustable width, said structure comprising amajor element II that constitutes the base and one side of the channel.and a minor element 26 that constitutes the other side of the channel.The major element is formed on its base portion, at the ends thereof,with respective slideways such as the slideway 21 that extends part wayacross said base as' shown, the minor element 25 formed with tongues(not shown) that are slidably received in the respective slideways. Thearrangement is such that the minor element 26 is movable relatively ofthe major element 25 to vary the width of the channel defined thereby.Adjustment of the position of the minor element 26 is effected by meansof an adjusting screw 28 that is threaded through an ear or flange 29formed integrally with the major element 25. the inner end of said screwbearing against the outwardly presented side oi the minor When thechannel ll and unit 8' .element, the outer end of the screw providedwith a handcrank 30. The sides of the channel defined by the elementsand 26 are divergent, and they engage the sides of the resilient unit Sinthe same manner as the channel structure I5 previously describedexcept that they do not engage the laterally projecting legs of theangle strips ill of the resilient unit. The resilient unit S is securedto a supporting structure 3| by bolts 32, 32, which bolts on one side ofthe structure extend through respective slots 33 formed in thesupportingstructure, transversely of the position of the mounting, toenable lateral movement of one strip iii of the resilient unitrelatively of the other lateral strip l0 thereof. The arrangement issuch that any desired pro-compression may be imparted to the rubberbodies of the resilient unit.

In the embodiment of the invention shown in Fig. 5 the resilient unit Sdiffers from the resilient units of the other embodiments of theinvention in that the angle strip on one side thereof, designated 35, isformed with a substantial boss 36, and is formed with transverselyextending slots 31 for receiving the bolts or cap screws 38 by whichthat side of the unit is secured to a supporting structure 39. Securedto the latter in spaced relation to the angle strip aforesaid is abracket 40 having an upstanding portion through which is threaded anadjusting screw 4 I The inner end of the latter is adapted to operateagainst the face of a boss 36 of the resilient unit, said face of saidboss being perpendicular to the supporting structure, the outer end ofthe screw being provided with a knob 42 by which the screw is manuallyoperated. A portion of the structure supported by the mounting is shownat 43. The arrangement provides adjustment means for varying thepro-compression of the mounting.

In the embodiment of the invention shown in Fig. 6 the resilient unit Sis mounted in a shallow groove 45in a supporting structure 46. The widthof the groove 45 is less than the overall width of the unit S so thatthe positioning of the angle strips of the latter in said grooverequires said strips to be forced toward each other with the result thatdeterminate pre-compression is imparted to the rubber elements of theunit.

Other modifications may be resorted to without departing from the spiritof the invention, or the scope thereof as defined by the appendedclaims.

What is claimed is:

1. In a resilient mounting of the character de-' scribed, thecombination of a resilient unit comprising a pair'of parallelspaced-apart, angular lateral strips each firmly attached to asupporting structure.'an intermediate strip spaced between and somewhatoffset from said lateral strips and attachable to a supported structure,and a pair of cushions of resilient material on opposite sides of saidintermediate strip each bonded to one lateral face thereof and to theconfronting face of a lateral strip, a bracket secured to the supportingstructure at one side of the resilient unit, an adjusting screw threadedthrough said bracket and engaging one of the lateral strips of theresilient unit whereby said latter strip may be moved relatively of theother lateral strip when said other lateral strip is attached to saidsupporting structure, and attachment means adapted to retain saidmovable strip in adjusted positions along a transversely extending slotin said movable strip.

2. In a device of the character described, the combination of a pair ofangular elements, one of which is fixed to a supporting structure andthe other is slidably positioned thereon, a U- shaped element disposedbetween said angular elements and in elevated relation thereto, a pairof resilient members extending from the confronting faces of the angularelements to the outwardly presented faces of ,the U-shaped element andbonded to said faces to provide the sole positioning means for saidU-shaped element, means operatively engaging said slidable angularelement for adjusting the position thereof to place said resilientmembers under determinate compresive stress, and means for securing theslidable angular element to the supporting structure in all positions ofadjustment thereon.

3. A resilient mounting of the character described having incombination, a supporting structure, a pair of spaced lateral stripsattached thereto, an element positioned intermediate said lateral stripsin spaced relation thereto, a pair of resilient elements disposedbetween the intermediate element and the respective lateral strips andbonded thereto, a bracket secured to the supporting structure at oneside of the mounting, and

a member threaded through saidbracket and operatively engaging one ofsaid lateral strips for adjusting the position thereof with relation tothe other lateral strip, the means attaching the adjustable lateralstrip to the supporting structure being operable in all positions ofadjustment thereof.

LE ROY M. KUBAUGH.

I REFERENCES CITED 7 The following references are of record in theRosenzweig Oct. 10, 1944

